Conventional intravascular ultrasound (IVUS) systems scan a disk-shaped plane emanating radially from a rotating single-element transducer or array transducer mounted on or within the body of a catheter. The scan provides a two-dimensional image representing a cross-section of the vessel or body through which the catheter passes. The two-dimensional scan can provide useful diagnostic information regarding lumen diameter and can identify localized anatomy, but the limited field of view provides little navigation or overall anatomy information to the user. Navigational information might be useful, for example, for more complex tasks such as delivering or retrieving stents or other vascular devices. These procedures are currently and typically used under the guidance of fluoroscopy.
It is possible to render three-dimensional images using an IVUS catheter by performing a pull-back scan with the catheter. The procedure involves beginning a two-dimensional scan and then pulling the catheter through the target anatomy at a known rate of speed, rapidly taking multiple two-dimensional images along the way. The collected images are then compiled into a three-dimensional model. The model, however, is only an historical snapshot of the anatomy and does not provide real-time three-dimensional views.
As a result, there remains a need for accurate and efficient application of ultrasound in three dimensions along a substantial length of a vessel or other bodily area, for example to provide a physician with a real-time view along that length. There also remains a need for devices that can view a medical device and one or more tissues or tissue parts simultaneously, particularly in cases in which the device and tissue(s) could not have been imaged reliably in any two-dimensional plane.